What shall we look into now?

John Ziman

Nearly half the essays in this book are about Einstein, and the way he searched for a unified Weltbild – a coherent image of all reality. His lifelong task as a scientist was to puzzle out the cosmic jigsaw. He succeeded in finding a link between the pieces labelled ‘electromagnetism’ and ‘mechanics’ and showed that the piece labelled ‘gravitation’ belonged next to the one labelled ‘geometry’, but he failed to fit them all together with a single formula. The advance of physics since Einstein’s heyday has not really solved that particular problem, even though two new forces have been uncovered and one of them is closely connected with electromagnetism.

Einstein is dead, but there is no awakening from the dream of a unified theory. It crept into the consciousness of the West in antiquity, was given flesh and blood by the Medieval Church, and was then redefined more starkly by Descartes and Newton. It became the leitmotiv of many great scientists such as Faraday and Helmholtz – not to mention a host of lesser figures such as Hans Christian Oersted, whose work is celebrated in one of these essays. Unification is the Supreme Project of Science, metaphysical and religious in inspiration. Curiosity can only end with an understanding of the nature of all things.

The integrity of Einstein’s scientific commitment was matched by his clarity concerning its means and ends. In his writings he is, as he said of God, ‘subtle, but not malicious’. From them Holton teases out his presuppositions, his approach to theory and experience, his ways of conceiving new models, and his attitude to the realities thus represented. An eloquent chapter analyses the accomplishments of the intellectual innovator as a shaper of the imagination of his era. Holton deals sharply with fashionable gurus who incorporate half-baked versions of relativity or quantum mechanics into their grand philosophical or theological schemes. Einstein’s thought was elevated, but he was no mystagogue.

Nor, indeed, did he regard his work as revolutionary. Scientists are well aware that they build on the solid achievements of the past. A novel contribution is seldom more than an extension or a revision of what everybody thought they knew already. The strength of Einstein’s bridge between electromagnetism and mechanics was that it linked structures that were solidly built and firmly based. Some modern philosophers of science – notably Thomas Kuhn – have since argued that such a development has to be considered a radical reformulation of the whole Weltbild. Einstein and his contemporaries always insisted that they could only see it as an evolutionary development within a continuous intellectual tradition.

In Holton’s own view, firm threads of historical continuity are provided by what he has taught us to call ‘themata’. In every era, scientists fall back on these ‘enduring elements ... somewhat like the old melodies to which each generation writes its new words’. Einstein, for example, was guided by long-established notions of formal symmetry and simplicity, of causality, completeness, continuity and cosmological scope. Another scientist – Niels Bohr, for example – might have favoured somewhat different thematic principles, but there was only a limited list from which either could have chosen. In fact, the measure of the greatness of both Einstein and Bohr is that each added one or two new and powerful themata to the common stock.

Thematic analysis must surely be one of the ways to an evolutionary account of the advancement of science. But it is not an easy path to understanding. In this latest book, Holton does not clear up my uncertainty about the distinction between a thema and a metaphor. Some of his themata – ‘atom’, for instance, and ‘field’ – undoubtedly have metaphorical roots, but he insists that not all scientific metaphors are to be counted as themata, however much insight they may convey. Where and how does he draw the line? It isn’t frivolous to point out that modern physics is using anthropomorphic metaphors, such as the ‘birth’ of a ‘strange’ particle, just at a time when psychology is studiously representing its findings in terms of strictly impersonal themata, such as ‘feedback’ and ‘data-banks’. Is this not another manifestation of that striving for a unified representation of the world?

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